The invention relates to a superconductive body of an oxidic superconductive material.
An oxidic superconductive material which comprises Ba, La, Cu and 0 is described in an article by J.G. Bednorz and K.A. Muller in Z.Phys.B - Condensed Matter 64, pp. 189-193 (1986). Ba may be replaced, for example, by Sr. The material described is superconductive at temperatures below a transition temperature T.sub.C of approximately 40K.
A superconductive material of the composition YBa.sub.2 Cu.sub.3 O.sub.7-.delta.' wherein .delta. has a value, for example, from 0 to 1, is described in an article by P.M. Grant et al. in Physical Review B, 35 (13), pp. 7242-7244 (1987). This material in which Y may be replaced inter alia by La and rare earth metals and in which Ba may be replaced, for example, by Sr, is superconductive at temperatures below T.sub.c .congruent.90K. Oxygen may be replaced partly by fluorine which results in an increase of T.sub.c.
These oxidic superconductive materials are characterized by having a high value of the transition temperature T.sub.c, which increases their usefulness However less favorable properties have impeded a wide application of these materials so far, especially when it relates to applications in which the superconductive material is not used in the form of a thin layer on a carrier. The critical current density, i.e. the current density above which the material is no longer superconductive, is too low for many applications. The resistance to moisture also is not satisfactory. The mechanical properties in particular are bad. The materials are brittle, have a low tear resistance and strength and a poor aging behaviour.